Lepow via Amazon offers the Lepow U-Stone Series 12,000mAh USB External Battery Pack, model no. L-US12000, in Stone Grey for $34.99. Coupon code "LEPOW915" cuts the price to $7. Plus, Prime members qualify for free shipping. (Non-members can spend $35 to qualify; otherwise, it adds $6.82.) That's $20 below our mention from July and the lowest total price we've seen for any 12,000mAh charger. It's compatible with most smartphones and tablets.